The present invention relates to a method and a device for receiving a downlink control signal in a wireless communication system. More specifically, the present invention relates to a device and a method for receiving control information, the method comprising the following steps: receiving a subframe which includes two slots; executing a blind decoding for a first control channel in the control channel search region within a first slot; decoding a second control channel using a specific resource within a second slot when the first control channel has been detected; and executing a blind decoding for the second control channel in the control channel search region within the second slot when the first control channel has not been detected.
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1. A method for receiving downlink control information in a wireless communication system, the method comprising:
receiving a subframe including a first slot and a second slot;
detecting a downlink grant including resource allocation bits in the first slot of a resource unit, each bit of the resource allocation bits corresponding to a respective resource unit;
blind decoding a uplink grant in the second slot of the resource unit, if a bit of the resource allocation bits corresponding to the resource unit is set to ‘0’; and
omitting blind decoding for the uplink grant in the second slot of the resource unit, if the bit of the resource allocation bits corresponding to the resource unit is set to ‘1’.
5. A method for transmitting downlink control information in a wireless communication system, the method comprising:
assigning a downlink grant including resource allocation bits in a first slot of a resource unit, each bit of the resource allocation bits corresponding to a respective resource unit; and
transmitting a subframe including the first slot and a second slot,
wherein the second slot of the resource unit is used as being a potential resource for assignment of a uplink grant, if a bit of the resource allocation bits corresponding to the resource unit is set to ‘0’, and
wherein the second slot of the resource unit is not used for assignment of the uplink grant, if a bit of the resource allocation bits corresponding to the resource unit is set to ‘1’.
3. A communication apparatus for receiving downlink control information in a wireless communication system, the communication apparatus comprising:
a radio frequency (RF) unit; and
a microprocessor configured to
receive a subframe including a first slot and a second slot,
detect a downlink grant including resource allocation bits in the first slot of a resource unit, each bit of the resource allocation bits corresponding to a respective resource unit,
blind decode a uplink grant in the second slot of the resource unit, if a bit of the resource allocation bits corresponding to the resource unit is set to ‘0’, and
omit blind decoding for the uplink grant in the second slot of the resource unit, if the bit of the resource allocation bits corresponding to the resource unit is set to ‘1’.
7. A communication apparatus for transmitting downlink control information in a wireless communication system, the communication apparatus comprising:
a radio frequency (RF) unit; and
a processor configured to
assign a downlink grant including resource allocation bits in a first slot of a resource unit, each bit of the resource allocation bits corresponding to a respective resource unit, and
transmit a subframe including the first slot and a second slot,
wherein the second slot of the resource unit is used as being a potential resource for assignment of a uplink grant, if a bit of the resource allocation bits corresponding to the resource unit is set to ‘0’, and
wherein the second slot of the resource unit is not used for assignment of the uplink grant, if a bit of the resource allocation bits corresponding to the resource unit is set to ‘1’.
4. The communication apparatus according to
8. The communication apparatus according to
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This application is the National Stage filing under 35 U.S.C. 371 of International Application No. PCT/KR2011/002704, filed on Apr. 15, 2011, which claims the benefit of U.S. Provisional Application Ser. No. 61/324,762, filed on Apr. 16, 2010, U.S. Provisional Application Ser. No. 61/327,086, filed on Apr. 22, 2010, and U.S. Provisional Application Ser. No. 61/382,471, filed on Sep. 13, 2010, the contents of which are all hereby incorporated by reference herein in their entirety.
The present invention relates to a wireless communication system, and more particularly, to a method and apparatus for receiving a downlink signal.
Wireless access systems have been widely deployed in order to provide various types of communication services including voice or data. In general, a wireless access system is a multiple access system that can support communication among multiple users by allowing them to share available system resources (a bandwidth, transmission power, etc.). Examples of multiple access systems include Code Division Multiple Access (CDMA), Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), Orthogonal Frequency Division Multiple Access (OFDMA), Single Carrier Frequency Division Multiple Access (SC-FDMA), Multi Carrier Frequency Division Multiple Access (MC-FDMA), etc.
An object of the present invention devised to solve the conventional problem is to provide a method and apparatus for efficiently using downlink resources in a wireless communication system.
It will be appreciated by persons skilled in the art that the objects that could be achieved with the present invention are not limited to what has been particularly described hereinabove and the above and other objects that the present invention could achieve will be more clearly understood from the following detailed description.
In an aspect of the present invention, a method for receiving downlink control information in a wireless communication system includes receiving a subframe including two slots, performing blind decoding for a first control channel in a control channel search space of a first slot, decoding a second control channel using predetermined resources in a second slot, when the first control channel has been detected, and performing blind decoding for the second control channel in a control channel search space of the second slot, when the first control channel has not been detected.
In another aspect of the present invention, a communication apparatus for receiving downlink control information in a wireless communication system includes a Radio Frequency (RF) unit, and a microprocessor. The microprocessor is configured to receive a subframe including two slots, perform blind decoding for a first control channel in a control channel search space of a first slot, decode a second control channel using predetermined resources in a second slot, when the first control channel has been detected, and perform blind decoding for the second control channel in a control channel search space of the second slot, when the first control channel has not been detected.
Preferably, the predetermined resources include the second slot of a resource block pair in which the first control channel has been detected.
Preferably, the predetermined resources are indicated by the first control channel.
Preferably, the control channel spaces of the first and second slots are configured independently.
Preferably, the first control channel carries a downlink grant and the second control channel carries an uplink grant.
According to the embodiments of the present invention, downlink resources can be efficiently used in a wireless communication system.
It will be appreciated by persons skilled in the art that the effects that can be achieved with the present invention are not limited to what has been particularly described hereinabove and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings.
The accompanying drawings, which are included to provide a further understanding of the invention, illustrate embodiments of the invention and together with the description serve to explain the principle of the invention.
In the drawings:
The configuration, operation, and other features of the present invention will readily be understood with embodiments of the present invention described with reference to the attached drawings. Embodiments of the present invention are applicable to a variety of wireless access technologies such as Code Division Multiple Access (CDMA), Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), Orthogonal Frequency Division Multiple Access (OFDMA), Single Carrier Frequency Division Multiple Access (SC-FDMA), and Multi Carrier Frequency Division Multiple Access (MC-FDMA). CDMA can be implemented into a radio technology such as Universal Terrestrial Radio Access (UTRA) or CDMA2000. TDMA can be implemented into a radio technology such as Global System for Mobile communications (GSM)/General Packet Radio Service (GPRS)/Enhanced Data Rates for GSM Evolution (EDGE). OFDMA can be implemented as a wireless technology such as Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wireless Fidelity (Wi-Fi)), IEEE 802.16 (Worldwide interoperability for Microwave Access (WiMAX)), IEEE 802.20, Evolved UTRA (E-UTRA). UTRA is a part of Universal Mobile Telecommunications System (UMTS). 3rd Generation Partnership Project Long Term Evolution (3GPP LTE) is a part of Evolved UMTS (E-UMTS) using E-UTRA. LTE-Advanced (LTE-A) is an evolution of 3GPP LTE.
While the following description is given of embodiments of the present invention with the appreciation that the technical features of the present invention are applied to a 3GPP system, this is purely exemplary and thus should not be construed as limiting the present invention.
Referring to
Referring to
The downlink slot structure illustrated in
Referring to
The PDCCH delivers information related to resource allocation for transport channels, a Paging CHannel (PCH) and a Downlink Shared CHannel (DL-SCH), an Uplink (UL) scheduling grant, and HARQ information to each UE or each UE group. The PCH and the DL-SCH are delivered on the PDSCH. Therefore, a Base Station (BS) and a User Equipment (UE) transmit and receive data on the PDSCH except for predetermined control information or predetermined service data. Control information carried on the PDCCH is called Downlink Control Information (DCI). The DCI transports uplink resource allocation information, downlink resource allocation information, or uplink transmission power control commands for UE groups. The BS determines a PDCCH format according to DCI directed to a UE and adds a Cyclic Redundancy Check (CRC) to control information. The CRC is masked by a unique Identifier (ID) (e.g. a Radio Network Temporary Identifier (RNTI)) according to the owner or usage of the PDCCH.
Referring to
Now a description will be given of RB mapping. Physical Resource Blocks (PRBs) and Virtual Resource Block (VRBs) are defined. PRBs are configured as illustrated in
where k denotes a subcarrier index and NscRB denotes the number of subcarriers in an RB.
A VRB is equal to a PRB in size. Two types of VRBs are defined, Localized VRBs (LVRBs) and Distributed VRBs (DVRBs). Irrespective of the VRB types, a pair of VRBs having the same VRB number nVRB are mapped to two RBs in the two slots of a subframe.
Referring to
TABLE 1
Gap (Ngap)
System BW
1st Gap
2nd Gap
(NRBDL)
(Ngap,1)
(Ngap,2)
5-10
┌NRBDL/2┐
N/A
11
4
N/A
12-19
8
N/A
20-26
12
N/A
27-44
18
N/A
45-49
27
N/A
50-63
27
9
64-79
32
16
80-110
48
16
Ngap denotes the frequency spacing (e.g. in units of a PRB) between PRBs in the first and second slots of a subframe, to which VRBs with the same VRB number are mapped. If 6≦NRBDL≦49, only one gap is defined (Ngap=Ngap,1). If 50≦NRBDL≦110, two gaps Ngap,1 and Ngap,2 are defined. Ngap=Ngap,1 or Ngap=Ngap,2 is signaled through downlink scheduling. DVRBs are numbered from 0 to NVRBDL−1. If Ngap=Ngap,1, NVRBDL=NVRB,gap1DL=2·min(Ngap,NRBDL−Ngap).
If Ngap=Ngap,2, NVRBDL=NVRB,gap2=└NRBDL/2Ngap┘·2Ngap. min(A, B) represents the smaller value between A and B.
ÑVRBDL consecutive VRB numbers form a VRB number interleaving unit. If Ngap=Ngap,1, ÑVRBDL=NVRBDL. If Ngap=Ngap,2, ÑVRBDL=2Ngap. VRB number interleaving may be performed using four columns and Nrow rows in each interleaving unit. Thus, Nrow=┌ÑVRBDL/(4P)┐·P where P denotes the size of a Resource Block Group (RBG). An RBG is defined as P consecutive RBs. VRB numbers are written in a matrix row by row and read from the matrix column by column. Nnull nulls are inserted into the last Nnull/2 rows of the second and fourth columns, and Nnull=4Nrow−ÑVRBDL. The nulls are neglected during reading.
Conventional LTE resource allocations will be described below.
A UE interprets an RA field according to a detected PDCCH DCI format. The RA field of each PDCCH includes two parts, an RA header field and actual RB allocation information. PDCCH DCI formats 1, 2 and 2A are the same in format for RA Type 0 and Type 1 and distinguished from one another by their 1-bit RA header fields according to a downlink system band. Specifically, RA Type 0 and RA Type 1 are indicated by 0 and 1, respectively. While PDCCH DCI formats 1, 2 and 2A are used for RA Type 0 or RA Type 1, PDCCH DCI formats 1A, 1B, 1C, and 1D are used for RA Type 2. A PDCCH DCI format with RA Type 2 does not include an RA header field.
Referring to
TABLE 2
System Bandwidth
RBG Size
NRBDL
(P)
≦10
1
11-26
2
27-63
3
64-110
4
The total number of RBGs, NRBG for a downlink system bandwidth of NRBDL PRBs is given by NRBG=┌NRBDL/P┐. Each of the └NRBDL/P┘. RBGs is of size P and if NRBDL mod P>0, one of the RBGs has a size of NRBDL−P·└NRBDL/P┘. Herein, mod represents a modulo operation, ┌ ┐ represents a ceiling function, and └ ┘ represents a flooring function. The size of the bitmap is NRBG and each bit of the bitmap corresponds to one RBG. The RBGs are indexed from 0 to NRGB−1 in an ascending order of frequency. RBG 0 to RBG NRGB−1 are sequentially mapped to the Most Significant Bit (MSB) to the Least Significant Bit (LSB) of the bitmap.
Referring to
NRBTYPE1=┌NRBDL/P┐−┌ log2(P)┐−1 [Equation 2]
The addressable PRB numbers of the selected RBG subset start from an offset, Δshift(p) with respect to the smallest PRB number within the selected RBG subset, which is mapped to the MSB of the bitmap. The offset is expressed as the number of PRBs and applied within the selected RBG subset. If the bit value of the second field for shifting a resource allocation span is set to 0, the offset for the RBG subset p is given by Δshift(p)=0. Otherwise, the offset for the RBG subset p is given by Δshift(p)=NRBRBG subset(p)−NRBTYPE1. NRBRBG subset (p) is the number of PRBs in the RGB subset p and is computed by
Referring to
RNs are classified into L1 RNs, L2 RNs, and L3 RNs according to their functionalities in multi-hop transmission. An L1 RN usually functions as a repeater. Thus, the L1 RN simply amplifies a signal received from a BS or a UE and transmits the amplified signal to the UE or the BS. Because the L1 RN does not decode a received signal, the transmission delay of the signal is short. Despite this benefit, noise is also amplified because the L1 RN does not separate the signal from the noise. To avert this problem, an advanced repeater or smart repeater capable of UL power control or self-interference cancellation may be used. The operation of an L2 RN may be depicted as decode-and-forward. The L2 RN can transmit user-plane traffic to L2. While the L2 RN does not amplify noise, decoding increases transmission delay. An L3 RN whose operation is depicted as self-backhauling can transmit an Internet Protocol (IP) packet to L3. As it is equipped with a Radio Resource Control (RRC) function, the L3 RN serves as a small-size eNB.
L1 and L2 RNs may be regarded as part of a donor cell covered by an eNB. In the case where an RN is a part of a donor cell, the RN does not have its own cell ID because it cannot control its cell and UEs of the cell. Nonetheless, the RN may still have a relay ID. At least part of Radio Resource Management (RRM) is controlled by the eNB to which the donor cell belongs, while part of the RRM may be located in the RN. An L3 RN can control its own cell. Then the L3 RN may manage one or more cells and each of the cells may have a unique physical-layer cell ID. The L3 RN may have the same RRM mechanism as an eNB. From the perspective of a UE, there is no difference between accessing a cell controlled by the L3 RN and accessing a cell controlled by a normal eNB.
RNs may be classified as follows according to mobility.
The following classifications can also be considered according to the links between RNs and networks.
Depending on a UE is aware of the existence of an RN, RNs are classified into the followings.
Embodiment 1
In
Now a description will be given of methods for allocating and transmitting control information and data in the resource configuration illustrated in
R-PDCCH/(R-)PDSCH Allocation and Demodulation
Control information is transmitted on an R-PDCCH and data is transmitted on an (R-)PDSCH. R-PDCCHs are divided into two categories. One category is a DL grant (DG) and the other category is a UL grant (UG). The DL grant contains information about time/frequency/space resources of an R-PDSCH corresponding to data to be received at an RN and information needed to decode the R-PDSCH. The UL grant contains information about time/frequency/space resources of an R-PUSCH corresponding to data to be transmitted from an RN and information needed to decode the R-PUSCH. With reference to the attached drawings, methods for allocating DL/UL grants to resource regions of a backhaul subframe and demodulating the DL/UL grants will be described below.
In
The existence of information (a), (b) or (c) in resource region 1-2 may be known from RA information (e.g. RBG or RB allocation information). For instance, if the RBG is all allocated to RN#1, RN#1 may determine whether information (a) or (b) is included in resource region 1-2 by interpreting RA information of the DL grant. Specifically, if resource region X-1 contains an RB or RBG in which a first R-PDCCH (e.g. a DL grant) directed to RN#1 is detected, RN#1 may assume that data for RN#1 exists in resources other than the resources of the first R-PDCCH in the corresponding RB or RBG. Accordingly, if the RA information indicates the existence of data in the corresponding RB or RBG, RN#1 may determine that R-PDCCHs other than the detected DL grant are not present in the corresponding RB or RBG. That is, RN#1 may determine that resource region 1-2 contains information (a). On the other hand, if the RA information indicates the absence of data in the corresponding RB or RBG, RN#1 may detect an appropriate data starting point (e.g. resource region 2-1), determining that a second R-PDCCH like information (b) or (c) exists. An eNB and the RN may assume that the size of the second R-PDCCH is unchanged. In case of information (c), RN#1 may determine that the second R-PDCCH is not a UL grant for RN#1 by attempting a CRC check using an RN ID. Meanwhile, even though RA information is used to identify information (a), (b) or (c), it may be implicitly set beforehand that an RBG carrying a DL grant is resources allocated to data for RN#1.
While a DL grant is shown in
Referring to
RN#1 may identify (a), (b) or (c) by blind decoding. It is preferred that data or control information for RN#1 is located in a resource region 2-X.
Additionally, RN#1 may identify (a), (b) or (c) using RA information (e.g. an RBG allocation bit) of the DL grant. For example, RN#1 may determine from the RA information whether resource region 2-1 carries data for RN#1 or a UL grant confined to resource region 2-1 (i.e. (a) or (b)) (Case A). RN#1 may also determine from the RA information whether resource regions 2-1 and 2-2 carry data for RN#1 or a UL grant confined to resource regions 2-1 and 2-2 (i.e. (a) or (c)) (Case B). To enable the RN to identify a UL grant or data in the resource regions, the eNB should set an eNB-RN operation on the premise of Case A or Case B. That is, RN#1 may distinguish (a) from (b) or (c) using the RA information (e.g. the RBG allocation bit). The case for which the RBG allocation bit is to be used should be preset. For example, it should be preliminarily preset that a UL grant is confined to resource region 2-1 or resource regions 2-1 and 2-2.
In the presence of a DL grant for RN#1 in resource regions 1-1 and 1-2, (a) data for RN#1 exists in resource regions 2-1 and 2-2 (not shown), (b) a DL or UL grant for another RN exists in resource region 2-1 (
On the assumption that there are only DL/UL grant sizes equal to a DL grant size in the above methods, the RBG allocation bit may indicate whether data or control information exists in resource region 2-1 or resource regions 2-1 and 2-2 and the size of a DL/UL grant (i.e. resource region 2-1 or resource regions 2-1 and 2-2) may be determined according to the size of the detected DL grant.
The above methods are applicable in the same manner to the case where a DL grant is located across resource regions 1-1, 1-2, and 1-3. In addition, the above methods are applicable in the same manner to the case where a UL grant is wholly or partially located across resource regions 1-1, 1-2, and 1-3. In this case, the RN blind-decodes a UL grant earlier than a DL grant in the above methods.
R-PDCCH Mapping and Detection at High Aggregation Level
The Relay-Control Channel Element (R-CCE) aggregation level (e.g. 1, 2, 4, 8, . . . ) of an R-PDCCH may change according to a channel environment, like the CCE set of an LTE PDCCH. Lets' assume that a DL grant of an R-PDCCH exists across three RBs and a UL grant is transmitted in the second slot of two RB pairs as illustrated in
The afore-described methods may be performed in a similar manner. That is, the existence or absence of a UL grant in the second slot may be indicated by an RBG allocation bit. Preferably, it may be assumed that an RBG having a DL grant is allocated to a corresponding RN. Accordingly, if a DL grant is located in the first slot, the RA bit of the corresponding RBG may indicate whether an R-PDSCH or a UL grant exists in the second slot. The following cases are possible.
The problem is to determine an RB pair or RB pairs carrying the UL grant. For instance, the number of RB pairs carrying the UL grant may vary according to an R-CCE aggregation level.
The number/positions of RB pairs carrying the UL grant may be determined by establishing a simple relationship between DL grant sizes and UL grant sizes. This will be described with reference to
Referring to
In an implementation example, it may be regulated that one R-CCE should exist in the first slot of an RB pair and two R-CCEs should exist in the second slot of the RB pair.
In this case, the first and second slots differ in R-CCE size. According to the implementation example, the DL grant aggregation level×2 may be preset to a UL grant aggregation level. Referring to
In another example, an R-CCE size may be defined on a slot basis. That is, each of the first and second slots of an RB pair may have one R-CCE. In this case, the R-CCEs of the first and second slots have different sizes. According to the example, the DL and UL grant aggregation levels may be preset to the same value. In
Referring to
In another method, the number of RBs occupied by a UL grant may be limited. For example, transmission of a UL grant may be confined to the second slot of one RB pair as is done for RN#1 in
Reinterpretation of an RBG allocation bit for the purpose of distinguishing a UL grant from data (an R-PDSCH) in the above description is possible on the assumption that a corresponding RBG is used only for a corresponding RN. However, if an RBG is to be used in the original meaning of its value, additional signaling is possible. The signaling may be transmitted on an R-PDCCH. Whether to use the additional signaling or reinterpret an RBG may be preset or signaled semi-statically.
If the RN fails to decode a UL grant even though the existence of the UL grant is indicated in the above methods, data (including the UL grant) existing in the corresponding slot may be combined with HARQ retransmission data. In this case, since the UL grant may cause a serious error to the HARQ-combined data, previous data that is likely to include a UL grant may be excluded from HARQ combining.
Embodiment 2
It is assumed in the example that a DL grant is transmitted in a starting part of an RB or RBG. When the eNB transmits DL and UL grants simultaneously in time to a specific RN, it is assumed that the UL grant shortly follows the DL grant in time. The DL grant may be delivered in the first slot of an RB or RBG and the UL grant may be delivered in the second slot of the RB or RBG. The data (the (R-) PDSCH) and the R-PDCCH are multiplexed in FDM, TDM, or a combination of both.
The RN monitors a specific area in which an R-PDCCH may be transmitted (an R-PDCCH search space) in order to detect the R-PDCCH. An R-PDCCH for a DL grant (DG) and an R-PDCCH for a UL grant (UG) are set independently for the RN. Accordingly, the RN blind-decodes the R-PDCCH search space for a DL grant (hereinafter, referred to as a DL SS) to detect the DL grant and blind-decodes the R-PDCCH search space for a UL grant (hereinafter, referred to as a UL SS) to detect the UL grant. Since the RN should attempt blind decoding in different R-PDCCH search spaces to detect the DL grant and the UL grant, blind decoding complexity may be increased.
With reference to
Referring to
Referring to
Referring to
Referring to
Referring to
Embodiment 3
In accordance with an embodiment of the present invention, the presence or absence of a UL grant or an (R-) PDSCH is indicated by a DCI RA field bit (or similar information) so that PDSCH data may be decoded successfully. For the convenience' sake, a resource allocation technique described herein conforms to LTE. The RA bit indicates whether a corresponding RB or RBG has been allocated for PDSCH transmission. It is assumed that if the RA bit is set to 0, the corresponding RB or RBG has not been allocated for (R-)PDSCH transmission and if the RA bit is set to 1, the corresponding RB or RBG has been allocated for (R-)PDSCH transmission, or vice versa. The meanings of the RA bit may be interpreted differently for a DL grant and a UL grant.
The DL grant and the UL grant may be located in RBs of different slots. For instance, the DL grant may exist in an RB of the first slot, whereas the UL grant may exist in an RB of the second slot. In this case, resource regions for DL data and the UL grant co-exist. Resources carrying the DL data are indicated by the RA of the DL grant and resources carrying the UL grant are detected by blind decoding. Accordingly, when the RN detects a UL grant in a resource region to which DL data is allocated, the RN receives/decodes the DL data in remaining resources except for resources carrying the UL grant (i.e. rate matching is performed). For the reason, this method is not preferable even though misdetection or false detection of a UL grant may affect DL data decoding.
To overcome the problem, the following constraint may be imposed on eNB-RN communication.
Referring to
For this purpose, if the RA bit is 1, the RN assumes that the RB or RBG carries no UL grant. On the other hand, if the RA bit is 0, the RN assumes that a UL grant may be transmitted in the corresponding RB or RBG. In this context, the eNB transmits a UL grant only in an RB or RBG with an RA bit set to 0. When the RN is not aware of the existence/position of a UL grant, it performs blind decoding. When the RN is aware of the existence of a UL grant, it decodes the UL grant at an indicated position. According to the above-described interpretation regarding an RA bit set to 0, the number of blind decodings for a UL grant can be reduced because a UL SS can be dynamically limited (or allocated) using a DL RA.
It has been described above that an RA bit set to 0 indicates resources available to a UL grant. However, this is purely exemplary and thus the RA bit set to 0 may imply that an RB or RBG with the RA bit actually carries a UL grant in a UL SS. In this case, the interpretation of an RA bit set to 0 may be confined to a specific RB or RBG. For instance, the interpretation of an RA bit set to 0 may be confined to an RB or RBG having a DL grant.
Considering data transmission, RA=0 may further be interpreted in the following manners. For instance, an RBG with RA=0 may deliver data when a DL grant or an R-PDCCH exists in the RBG ((a) and (b)). In another example, no data transmission may occur in the RBG with RA=0 irrespective of the presence or absence of an R-PDCCH in the RBG ((c) and (d)).
In
Referring to
Case 1A: the RN is aware of the position of a UL grant.
Case 1B: the RN is not aware of the position of a UL grant.
Case 2A: the RN assumes the absence of a UL grant. This case is based on the premise that the DL grant indicates the position of the UL grant.
Case 2B: the RN searches for a UL grant in the second slot.
For Case 1A, an appropriate rule may be set so that the position of a UL grant may be indicated by a DL grant. For instance, the DL grant may indicate information about the existence and/or position of the UL grant (shortly, UL grant position information) to the RN explicitly or implicitly. In a method, the existence of the DL grant itself means the UL grant position information. In another method, a type indication field (1 bit) used to distinguish DCI format 0 from DCI format 1A in the legacy LTE system may be used to indicate the UL grant position information. Since the UL grant position information is 1 bit in the first and second methods, only the existence of a UL grant may be indicated. Therefore, the first and second methods are based on the assumption that a certain rule is set between the positions of DL and UL grants. For example, it may be assumed that the DL and UL grants are in the same RB pair. In a third method, the DL grant may include UL grant position information of 2 or more bits. In this case, the UL grant position information may indicate the absence of a UL grant or one of a plurality of UL grant position candidates. In a fourth method, UL grant position information may be indicated by a combination of RRC signaling and a DL grant. For example, one or more of a plurality of UL grant position candidates are indicated by RRC signaling and the absence or actual position of a UL grant is indicated by a DL grant.
Referring to
In Case 1B, the RN does not know the existence/position of a UL grant. Thus, when the RN fails in blind decoding of a UL grant, the failed blind decoding may affect (R-)PDSCH decoding. For example, misdetection of a UL grant, i.e. failure to detect the UL grant may be mistaken for existence of an (R-)PDSCH in UL grant transmission resources. As a result, an (R-)PDSCH decoding error may be caused because UL grant information is used for (R-)PDSCH decoding. False UL grant detection also leads to a problem. In this case, the RN wrongly determines that a UL grant is present in (R-)PDSCH transmission resources. The resulting exclusion of (R-)PDSCH information corresponding to the UL grant resources during (R-)PDSCH decoding may cause an (R-)PDSCH decoding error. The problems encountered with UL grant misdetection/false detection can be avoided depending on implementation in Case 1B. In an implementation example, it may be regulated that UL grant resources (e.g. a UL SS or actual UL grant transmission resources) should not be allocated to an (R-) PDSCH. However, this imposes a constraint on (R-)PDSCH scheduling. Since a resource allocation unit is large in RA Type 0/2, the scheduling constraint becomes more serious.
In Case 2B, since no DL grant is detected in the first slot, the RN determines that an (R-)PDSCH is not transmitted. Non-detection of a DL grant may amount to actual non-transmission of a DL grant or missing of a DL grant. Since the RN does not perform (R-)PDSCH decoding in either case, the (R-)PDSCH decoding problem caused by misdetection/false detection of a UL grant described in Case 1B is not generated.
Referring to
Referring to
In contrast, when the RN fails to detect the DL grant in the first slot, the RN does not know the existence/position of the UL grant in the second slot. In this example, if the RN does not know the existence/position of the UL grant due to the failure in detecting the DL grant, the RN performs blind decoding in the UL SS to detect the UL grant in the second slot (Case 2B). Since no DL grant is detected in the first slot, the RN determines that an (R-)PDSCH is not transmitted to the RN. In this case, the (R-)PDSCH decoding problem caused by misdetection/false detection of a UL grant as described before with reference to
In a combination of Case 1A and Case 2B, the RN performs blind decoding unconditionally for a DL grant, whereas the RN performs blind decoding for a UL grant under a condition, that is, only when the RN fails in detecting a DL grant. Therefore, the probability of missing a UL grant can be decreased. Further, consumption of UL grant transmission resources or granted UL resources that may be caused by the failure in detecting a UL grant can be minimized.
While the above description is made centering on the relationship between an eNB and an RN, the same thing or a similar thing is applicable to the relationship between an RN and a UE. For instance, the eNB and the RN may be replaced with the RN and the UE, respectively in the above description.
Referring to
The BS 110 includes a processor 112, a memory 114, and a Radio Frequency (RF) unit 116. The processor 112 may be configured so as to implement the proposed procedures and/or methods according to the present invention. The memory 114 is connected to the processor 112 and stores various types of information related to the operations of the processor 112. The RF unit 116 is connected to the processor 112 and transmits and/or receives a radio signal. The RN 120 includes a processor 122, a memory 124, and an RF unit 126. The processor 122 may be configured so as to implement the proposed procedures and/or methods according to the present invention. The memory 124 is connected to the processor 122 and stores various types of information related to the operations of the processor 122. The RF unit 126 is connected to the processor 122 and transmits and/or receives a radio signal. The UE 130 includes a processor 132, a memory 134, and an RF unit 136. The processor 132 may be configured so as to implement the proposed procedures and/or methods according to the present invention. The memory 134 is connected to the processor 132 and stores various types of information related to the operations of the processor 132. The RF unit 136 is connected to the processor 132 and transmits and/or receives a radio signal. The BS 110, the RN 120, and/or the UE 130 may have a single antenna or multiple antennas.
The embodiments of the present invention described above are combinations of elements and features of the present invention. The elements or features may be considered selective unless otherwise mentioned. Each element or feature may be practiced without being combined with other elements or features. Further, an embodiment of the present invention may be constructed by combining parts of the elements and/or features. Operation orders described in embodiments of the present invention may be rearranged. Some constructions of any one embodiment may be included in another embodiment and may be replaced with corresponding constructions of another embodiment. It is obvious to those skilled in the art that claims that are not explicitly cited in each other in the appended claims may be presented in combination as an embodiment of the present invention or included as a new claim by a subsequent amendment after the application is filed.
In the embodiments of the present invention, a description is made, centering on a data transmission and reception relationship among a BS and a UE. In some cases, a specific operation described as performed by the BS may be performed by an upper node of the BS. Namely, it is apparent that, in a network comprised of a plurality of network nodes including a BS, various operations performed for communication with a UE may be performed by the BS, or network nodes other than the BS. The term ‘BS’ may be replaced with the term, fixed station, Node B, eNode B (eNB), access point, etc.
The embodiments of the present invention may be achieved by various means, for example, hardware, firmware, software, or a combination thereof. In a hardware configuration, an embodiment of the present invention may be achieved by one or more ASICs (application specific integrated circuits), DSPs (digital signal processors), DSDPs (digital signal processing devices), PLDs (programmable logic devices), FPGAs (field programmable gate arrays), processors, controllers, microcontrollers, microprocessors, etc.
In a firmware or software configuration, an embodiment of the present invention may be implemented in the form of a module, a procedure, a function, etc. Software code may be stored in a memory unit and executed by a processor. The memory unit is located at the interior or exterior of the processor and may transmit and receive data to and from the processor via various known means.
Those skilled in the art will appreciate that the present invention may be carried out in other specific ways than those set forth herein without departing from the spirit and essential characteristics of the present invention. The above embodiments are therefore to be construed in all aspects as illustrative and not restrictive. The scope of the invention should be determined by the appended claims and their legal equivalents, not by the above description, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.
Industrial Applicability
The present invention relates to a wireless communication system. Particularly, the present invention is applicable to an eNB, an RN and a UE.
Seo, Hanbyul, Kim, Byounghoon, Kim, Kijun, Kim, Hakseong, Lee, Daewon
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Oct 12 2012 | KIM, HAKSEONG | LG Electronics Inc | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 029140 | /0303 | |
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